Seriously, there has to be a good reason why fish fertilizer has been used for thousands of years. So we called in organic expert and gardener extraordinaire Jeff Lowenfels to give us the lowdown on the various products available that are derived from our aquatic friends.

American kindergarteners are taught the story of Squanto, a Native American who showed the Plymouth Rock pilgrims how to use fish to fertilize their corn plants. Egyptian children learn about their ancestors using fish to feed plants along the Nile, and Peruvian youths are taught that their pre-Columbian ancestors put a kernel of corn into the mouth of a fish and planted the whole thing.

My Grandfather, an avid gardener and fisherman, was my Squanto. He taught me to bury fish guts and too-bony-to-eat-fish in the rose garden and beneath the tomato plants. The results were outstanding. I’ve been hooked, if you will pardon the pun, on fish as great fertilizer ever since.

What is Fish Fertilizer?

Obviously, fish fertilizer is fertilizer made from fish or fish parts. However, not all fish fertilizers have the same characteristics. In fact, there are actually three different categories of fish fertilizer, so don’t just walk into a store and pick up whatever is on the shelves without doing a bit of homework first.

Each category of fish fertilizer is made using a different process and the products that result, contain varying amounts of nutrients. There are also best uses and special problems, so it is important to know a bit about fish fertilizers before you wade into the water (sorry, I can’t help myself!) and start using them.

In sum, the three categories of fish fertilizers are: fish meals, fish emulsions and fish hydrolysates.  Fish meals are made by grinding fish carcasses after a heating process has removed much of the oils. Wastewater left over from making fish meal can be concentrated to produce fish emulsions. Finally, fish digested in vats using enzymes instead of heat produces fish fertilizers called hydrolysates.

Large Tank of Fresh Fish Hydrolysate

The word “fish” can refer to both a single fish or plural when referring to fish in general or to a quantity of fish of the same kind; the word “fishes” is a special kind of plural used to refer to a quantity of various types of fish.

What types of fish are processed into Fish Fertilizer?

Virtually any kind of fish can be made into a fertilizer. However, fish are usually divided into two groups. The first are fish harvested for human consumption. These include tuna, salmon, catfish, halibut, bass, anchovies and sardines. Fish processed specifically to make products for plants and animals make up the second group. These include pollack, menhaden and herring.

What are the advantages of Fish Fertilizer?

Fish fertilizers have several advantages over their chemical counterparts. First, they can be totally organic with all the benefits associated with improved soil structure, increased microbial life and better plant health. Second, fish fertilizers don’t burn plants as readily as chemical fertilizers. Fish fertilizers generally have slower release rates and they don’t need to be applied as often. Moreover, fish fertilizers are not readily leached from the soil, rather they are held in the bodies of the microbes that turn then into plant food. Finally, they often contain trace nutrients not found in chemical formulas.

Characteristics of Fish Fertilizer

The characteristics of a fish fertilizer are based on the way it is processed as well as what is in the fish used. Processing methods are either listed on the label or implied by the name of the kind of fertilizer.

Fish Hydrolysates

These fish fertilizers are made from whole fresh fish, or fresh fish scraps, which are digested using special enzymes that break down the large proteins in fish meat and bones. Enzymatic digestion is known as hydrolysis, hence the name hydrolysates for the liquid mixtures that result. These liquids are like thick fishy milkshakes. Phosphoric acid is added to the mixtures to halt the digestion process. As a result, the pH of hydrolysates is usually lower than other kinds of fish fertilizers. Also they don’t smell nearly as bad.

Generally, fish hydrolysates have an NPK analysis around 2:3:0, 2:4:1 or 2:5:0. Because no heat is involved in making the fertilizer, and nothing is removed from the fish, hydrolysates contain more of a fish’s proteins, hormones, trace elements and vitamins than do other kinds of fish fertilizers. Application requires dilution to about five or six teaspoons per gallon of water. Fish hydrolysates can be used in all stages of growing.

Finally, unlike the other two kinds of fertilizers, hydrolysates contain all of the fish oils. These oils are excellent beneficial fungal foods, which make fish hydrolysates a good nutrient source for maintaining and increasing soil fungal populations.

Hydrolyzed fish is widely considered to be the “high-end” fish fertilizer product. It doesn’t have a highly objectionable odor like fish emulsion and it’s also highly water-soluble, so it’s great for drippers and foliar applications. It also contains higher levels of phosphorus than fish emulsion products.

Fish Meals

Fish is often heated to remove fats and oils to use in various products. The lean carcasses that remain are ground up into a meal and sprayed with phosphoric or sulfuric acid for stabilization and deodorization. Unlike hydrolysates and emulsions, fish meals are not liquid. They have more protein than emulsions, but less than hydrolysates.

Fish meals usually have an NPK analysis around 10:6:2 or 12:6:2. The high nitrogen obviously makes them good for vegetative growth and the relatively high phosphorus content makes fish meals good for root development, too. The down side is that fish meals have a strong odor.

Fish meals are granular or powder in form, and are usually applied at a rate of 5 to 10 pounds per 100 square feet. They continue to smell for a few days and are therefore usually buried into the root zone. They are not recommended for indoor use because of their odor, but if you can stand the smell, they can be mixed into soils where they act as a slow release fertilizer.

Fish meal is a good soil conditioner for use early in the outdoor growing season—it’s ideal in new vegetable or flower beds because it will help root development. Although most fish-meal fertilizers will last for 6-8 months, most of the benefits are realized in the first few months.

Fish Emulsions

After oils, fats and proteins are removed from fish, a liquid slurry is all that remains. This slurry can be concentrated by evaporating up to half of its liquid, resulting in a syrupy emulsion suitable for use as a fertilizer.  Some phosphoric acid is added to stabilize and deodorize things. This lowers the pH of the emulsions, which is still not as low as that of hydrolysates.

The cooking segment of the fish emulsion manufacturing process destroys a lot of the fish “goodies” such as the vitamins and hormones so useful to plants and microbes. There is much less protein in emulsions, and fewer solids, but the upside is that fish emulsion is more soluble than other fish fertilizers and cheaper, too.

Fish emulsions have an NPK analysis of 5:2:2 or 5:1:1, even though they are known for their micronutrient content. As the most soluble fish fertilizers, they are good for foliar feeding.

The fish used to make emulsions are usually “trash” fish, which are harvested only for this purpose and not for consumption by humans. They often contain toxics. Menhaden, for example, spend part of their lives in waters that are heavily polluted with metals. Some freshwater fish that can’t be eaten because they are polluted are also often processed into fish emulsions.

Moreover, if the steam employed to strip oils from the fish is from a municipal source, it usually contains chlorine. When the final liquid is concentrated, so is the chlorine—reportedly up to as much as 50%. Chlorine can be harmful to plants and beneficial soil microbes, so you might want to review product MSDS reports to make sure what you buy isn’t too loaded with chlorine.

Application rates of fish emulsions generally run about five or six tablespoons per gallon of water. Fish emulsions are often used in mixtures made up of kelps, other seaweeds and crab shells. They sometimes contain additional materials to raise the NPK. These may not be bad, but you need to take into account what they provide before using these fish fertilizers on your plants.

The nitrogen contained in fish emulsion is released more gradually than in many other non-fish-based fertilizers. Fish themselves naturally contain about 2.3% nitrogen.  However, some fish emulsion products contain synthetic sources of nitrogen, such as urea, to boost the nitrogen percentage. Be sure to check with the manufacturer to find out if their fish emulsion product is comprised only of organic inputs.

Hydrolysate and Emulsion Process (image credit - Dramm Corporation)

Common Objections to Fish Fertilizers

There are some basic objections to using fish fertilizers, which may help you decide to use one versus another.

It Stinks!

One of the biggest concerns about using some fish fertilizers is their smell. Fish meals, for example, smell horrendously. The odor goes away after a few days but using the stuff inside might be problematic, even for those growers with the largest carbon filters! Fish emulsions can also have a strong, offensive odor even when deodorizing agents are added to them. Generally, hydrolysates have much less, if any, offensive odor.

While humans may take offense to the smells of fish meals and emulsions, many pets and pests find the odor attractive. Cats, dogs and raccoons love to eat fishmeal and some dogs like to roll in it. If you are concerned about animals disturbing your plants, take protective action.

Toxins

Adding to the problems caused by high concentrations of chlorine in the steam water used to cook some fish fertilizers are the existence of other toxins. Some fish fertilizers contain heavy metals like mercury, which are found in fish living at the top of food chains. Concentrating solutions when making emulsions also concentrates these toxins. However, these fertilizers may still be fine for inedible plants.

Unfortunately, the amount of toxins in a fish fertilizer is not going to be listed on the label. However, you can look up individual fertilizers by—to determine any heavy metal content—on a great website maintained by the Washington State Department of Agriculture.

Sustainability

No one should ever buy fish fertilizer made from endangered or depleted fish stocks and some argue that there are good reasons not to buy any fish fertilizer made from “trash” fish. For the most conscientious growers, only waste fish and fish wastes from human consumed fish are acceptable.  Again, a little snooping around on the Internet can provide you with the valuable information needed to make a rational purchasing decision.

In this day and age, there are other sustainability considerations. Packaging, energy resources spent on processing and transportation, as well as additives used are all inputs to making a choice as to which category or brand of fish fertilizer to purchase. Again, a little research is worth it in terms of environmental, plant and human health.

Suitability for hydroponics and foliar applications

Fish emulsions and fish hydrolysates can be used in hydroponics systems because they are liquid in form. Emulsions are more soluble and some of their nutrients are plant useable without beneficial microbiology, but both work best in organic systems with microbes. Odor is a concern, especially with emulsions, and toxins may be as well. If you use a filter in your system, fish hydrolysates may need straining to prevent clogging the filter’s fine mesh screen.

All of the major hydroponics companies sell fish based hydroponics fertilizers. They also supply lots of information to promote them, but read labels carefully and fish (ouch!) for the necessary information to make an informed decision. You can also request MSDS (material safety data sheets) from these companies.

Fish fertilizers as a catalyst for beneficial biology

Organic fish fertilizers excel at supporting the microbe herd that is at the base of the soil food web. They all provide some NPK and most, at least those made from sea fish, also provide trace elements, micronutrients and other good stuff.

Fish hydrolysates, in particular, come about as close to duplicating the practice of burying a whole fish. Only the hydrolysis process makes the fish more available to microbes, breaking down large molecules into tiny ones. Microbes can and do happily feed off the organic matter and proteins from the meat and guts. Calcium from the fish bones is also retained in hydrolysates. And, as noted, the oils in hydrosylates make great fungal food for those plants that prefer fungal dominated soils: perennials, trees and shrubs. For this reason, hydrolysates make great fungal food for compost teas.

Fish meals, too, support loads of microbial activity. They contain tremendous amounts of protein and are great foods for bacteria, and annuals and vegetables that prefer a bacterial dominance in their soil. Covered with bacteria, fishmeal added to a compost pile gets the pile cooking due to its high microbial metabolism. In addition, flies (and their larvae) love it, which in turn attracts other members of the soil food web.

Fish Fertilizers: Be an educated consumer

Not all products sold as fish fertilizers are made just from fish. Some contain non-fish additives as previously mentioned—primarily seaweed and crab shell. The seaweeds are full of micronutrients, auxins and cytokinins; crab shells provide chitin found in the cell walls of fungi. Sometimes, however, non-organic materials are added to boost NPK, so always read the labels on fish fertilizers.

The right fish fertilizers, or combinations thereof, can be great for your plants. Fish hydrolysates provide more nutrients and vitamins, hormones and micronutrients. Fish meals are slower acting, more suitable for outdoor use and larger areas.  Fish emulsions are ideal for quick-acting foliar sprays.

However, while fish fertilizers can be extremely useful, do your homework before buying. Research the web, read labels and know what to ask for and you won’t go wrong.

Words: Jeff Lowenfels – author of the best selling gardening book “Teaming With Microbes: The Organic Gardener’s Guide to the Soil Food Web” from Timber Press.
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Borlaug grew up in a remote corner of rural Iowa – a place with twelve- grade one-room schools from which most youngsters dropped out by the eighth grade, a place with one car, no telephones, no electricity, but the Iowa Corn Song ,3 proudly sung like the Star-Spangled Banner at the start of every school day:

There was no future, other than growing corn, but “Norm Boy’s” grandfather had another vision, and inculcated the boy with a determination to obtain a higher education. He arrived at the University of Minnesota at age 20, “as a student athlete [whose] ability to do university work was questioned” 4 but left years later clutching a Ph.D in plant pathology,.

Assigned during World War II to Dupont, where he helped to develop DDT as part of the war effort, Borlaug was offered the sky, but given the choice between Dupont and sub-subsistence science for sub-subsistence Mexican farmers, he chose the. latter, working. with the Rockefeller Foundation, in a project to stave off a looming food crisis in overpopulated Mexico.5

THE AGRICULTURAL END OF FOOD PRODUCTION USES STAGGERING AMOUNTS OF WATER. AS AN ILLUSTRATION, HERE’S A RECIPE FOR A QUARTER-POUND CHEESEBURGER

The project goal was to breed strains of wheat that could withstand adverse climates, survive wheat’s fungal diseases, and produce prodigiously on dwarf plants, then convince tradition-bound farmers to adopt forthwith the new hybrids and the technology that accompanied them.. It was a race against time, and an extraordinarily demanding task in the pre-DNA era. Borlaug set up field operations in two locations with disparate climates and growing seasons so he could have plants accustomed to multiple climates, and could grow two generations of seedlings each year.

Borlaug shortly achieved his goal, and Mexico’s food crisis was over in a decade. On to Asia, where the same thing was happening: overpopulation, courtesy of modern medicine.. India was home to some of the poorest people in the world. Famine was widely forecast for the mid-seventies. It was the era of Ehrlich’s Population Bomb. Stanford professor Ehrlich was an icon for the rising environmental movement, but overnight, stubborn farm boy Borlaug appeared to prove him wrong. In a few short years, the Green Revolution turned a land of undernourished millions into the second largest wheat producer in the world. Borlaug became the hero of millions of peasants, and also of those who spoke for unlimited growth, and in the next twenty years The Population Bomb disappeared from the environmentalist lexicon, leaving the population boom unquestioned.

The Green Revolution, which was to go on producing wonder strains for other crops and other countries, had three central parts. The other two were irrigation and chemical fertilizer. These changed agriculture fundamentally, from a primarily solar-energy craft dependent upon local weather and soil conditions, to a fossil-fuel technology designed to force the land to produce mightily regardless of its natural limitations. Borlaug, summarizing in his Nobel lecture, warned that the new hybrids had not resulted in major yield improvements without both irrigation and “a strong responsiveness and high efficiency in the use of heavy doses of fertilizers.”6 Plentiful water, plentiful chemical fertilizer – that’s the secret to how in the last half century India – and California – turned arid lands almost instantly into wildly productive garden baskets. It may not be a sustainable solution, but at the time, the world needed a quick fix.

In his Nobel lecture, Borlaug talked proudly about how the new practices had given near-starving subsistence farmers surpluses they could sell, the money to buy oil-driven water pumps and tractors, and the influence to insist upon doors opening to the broader world. If you’ll permit me a broad brush, the Green Revolution had doubled and tripled grain production for multi-millions who had been on the brink of starvation, but turned locally self-sustaining agriculture into hydroponics. And it turned subsistence farmers, dependent on the whims of the soil, sun and rain, into small-time contractors dependent on the whims of the discount rate, the commodities markets and the petrochemical industry.

It weakened their umbilical cord to Mother Earth, and eased a process in which millions would find themselves drawn to seek their fortunes in the cities, providing cheap labor to run the Indochinese economic machine. But those were events far in the future when Borlaug performed his magic, and it’s hard to quibble when several hundred million people are about to die of starvation..

The agricultural end of food production uses staggering amounts of water. As an illustration, here’s the author’s recipe for a quarter-pound cheeseburger:

Ingredient /Water used in production

Lettuce (1/4 cup)…………………………0.8 gal

Bun (2 bread slices equiv) …………………….. 22.0 gal

Tomato (1 oz paste equiv) ……………………. 6.1 gal

Cheese (1 oz.)……………………………………… 58.3 gal

Ground beef (4 oz) ………………………………..641.2 gal

TOTAL………………………………… 728.4 gal

8-oz. Glass of milk……………………… 50.0 gal 7

The reason water consumption for meat and dairy products is so much higher than for vegetables and grain, is that, very approximately, it takes two pounds of grain to produce a pound of chicken, five pounds to produce a pound of pork, and ten pounds to produce a pound of beef.

The Green Revolution doubled the world’s irrigated acreage from 346 million acres to 690 million acres, and increased by a factor of nearly five its consumption of chemical fertilizer .8 Where does all the irrigation water come from? Wells, largely; as the World Bank has pointed out, groundwater comprises 97% of the world’s accessible freshwater reserves.9

Wells are a classic case of Garrett Hardin’s “tragedy of the commons” 10 – if the aquifer is shared by multiple individuals or multiple villages and there are no rules on how much anyone can use, then the users are individually, although not collectively, better off if they use as much as they want until the wells all run dry. So unless everyone follows the Golden Rule or there is an elaborate legal “groundwater management plan,” controlling how much everyone gets, the wells DO run dry. The first thing you need to begin fair and sustainable allocation of groundwater supplies is records of pumping from wells. They don’t exist. And farmers everywhere, from the one-acre plots of North China to the 1000-acre ranches of California, rebel against interference with their freedom. Even if there were the will and the way to adopt rational groundwater management programs around the world, the task would take many decades to accomplish – unless another farm-boy-savior-scientist comes down from the sky, to whom the farmers and bureaucrats can relate.

So where does that leave us? The United States is in a relatively good position because only one fifth of its grain production comes from irrigated land, but the figure is three fifths in India and four fifths in China.11 The world-wide picture is bleak:

* The annual overdraft from the U.S. Ogallala Aquifer, producing cattle and grain in quantity, is said to be about equal to total yearly flow of the Colorado River.12 It was declared by the USDA over a decade ago to be “near depletion,” with Texas having already lost 1.4 million acres of irrigated land and the irrigated land supported by the aquifer expected to be reduced 50% by2030, an acreage accounting for roughly 10% of US grain production.

* In China, the world’s greatest grain producer,13 pumping from a fossil aquifer in the North China Plain is relied upon to produce half the nation’s wheat and a third of its corn, approximately 40 million tons per year or 10% of the nation’s grain production; 14.

* Northern India is also overdrawing its groundwater supplies to maintain grain production. Although the overdraft is apparently much less severe than in China or the United States, nonetheless, if the current level of unsustainable groundwater overdraft continues, government experts have concluded that “India could face severe water shortages.”15

* Lester Brown, founder of the Worldwatch Institute, reports that fifteen nations containing half the world’s population, rely on groundwater overdraft for irrigation.16

These practices cannot go on for long, and in this writer’s opinion, water development and conservation are unlikely to come to the rescue. large surface reservoirs and desalinization are unlikely to save the day, because these projects do not ordinarily pay for themselves and for the foreseeable future governments are unlikely to be in a position to subsidize multi-billion-dollar investments in concrete and steel to feed the poor. As for water use efficiency, it might theoretically permit savings of anywhere from 10-40%, but implementation and enforcement have all the hurdles of groundwater management plans, plus the additional hurdle that tens of millions of farmers were taught decades ago that plentiful water was essential to high yields. Changes may occur, but they will most likely be incremental and slow. So dropping grain production appears inevitable in the US and China, and likely in much of the rest of the world, in the absence of major increases in acreage and/or yield per acre.

As for increased acreage, there is general agreement that the acreages have been at best essentially “flat” for decades17 and in any event it is hard to envision major investments being made in land development to feed the undernourished and virtually destitute bottom seventh of our population when the same land could be used, if at all, to produce beef or biofuels for the top seventh.

Yields? They are still increasing at approximately 1% per year, not enough to keep up with population increase; in fact, world per capita grain production peaked in 1986.18 Steady 1% per year yield increases cannot, of course, solve the problem of exhaustion of fossil aquifers, likely to occur close to the same time as exhaustion of the oil supply. There are disputes as to whether or how long genetic tinkering can continue to improve yields. Eventually we have to hit the maximum efficiency at which photosynthesis can occur, but there are radically different educated views as to how close we are.19

In Lester Brown’s view, “Unless population growth can be slowed quickly, there may not be a humane solution to the emerging world water shortage.”20 The statistics appear to show that he should have said population growth must be “reversed quickly,” rather than merely “slowed quickly.”

So when the aquifers run dry, a return to the days when agriculture was limited to natural precipitation, is inevitable. This means, on top of the present inability of yield increases to keep up with population increases, a relatively abrupt loss of at least 10% of production.

What about the fertilizer? That comes from mining operations, too. That is literally true of phosphorus, although it wasn’t before we came along. There are more phosphorus-rich bones walking the face of the earth than ever before in geological history; humanity is hoofing it around with 5 billion kg or 11 billion pounds of phosphorus ,21 which comes from mines,22 – NONE of it recycled. This has happened only since half of us moved to the cities, taking our personal wastes with us; petrochemical fertilizers replaced natural ones; and community sewers were invented. Mama Nature can’t afford this kind of progress for long.

In fact, the world phosphorus reserves are expected to be depleted within 25 to 70 years, depending upon where you are. Humanity will apparently go extinct for lack of phosphorus within a century unless we resume recycling,.23 This writer is unaware of any government plans anywhere, to do so.

And phosphorus isn’t the perceived serious problem. Nitrogen is. We have a reasonable amount of nitrogen in the air for the present, but the nitrogen has to be processed into ammonium nitrate or something comparable with a high energy input, and the starting material is natural gas, 5 % of which globally is used for production of nitrogen fertilizers.24 There are presently no alternatives. Natural gas accounts for 90% of the cost of nitrogen fertilizer, so the cost of the latter is pretty much proportional to the cost of the former.25 When the petroleum supply starts to go, fertilizer prices will spiral upward.

Of course nitrogen fertilizer can also be produced by nitrogen-fixing legumes, but that necessitates alternating between nitrogen-fixers and market crops. In his Nobel lecture Borlaug spoke of a dream of nitrogen-fixing grains being introduced in 1990 that would free peasant farmers from the need to purchase chemical fertilizers, but then, he said, he would wake up, disillusioned. It was only a dream. 35 years and 3 billion more people later, he would have to tell the New York Times, “This is a basic problem, to feed 6.6 billion people. Without chemical fertilizer, forget it. The game is over.”26

So at present, grain yield is not keeping up with the population, and things will get worse as fertilizer and water become expensive and scarce. Will a large part of the population die when they are curtailed? Not necessarily, because of how we allocate the use of the grain we produce.

To see the whole picture, we need to understand a little about the grain market, which is the dominant food market.. There are at this time three competing demands for the commodity: food (i.e. direct consumption by people), fodder, and fuel. Before fuel became part of the mix, the division between food and fodder was 60:40, with the “fodder” component capable if used as food, of providing the caloric needs of 3.5 billion people.27 But we are squandering the 40% “cushion.”

The mix in 2008 was said by Worldwatch Institute to be 47% food, 35% fodder, 18% fuel. The 18% figure may not be a 2010 reality, but no one claims less than 9%, and use of grain for bioalcohol is projected to double in the next decade.28 The 18% that we burn or apparently will burn is more than sufficient to fill the stomachs of the record 1 billion people who are undernourished today. Does it give you a warm and fuzzy feeling that we burn the grain that is sufficient to eliminate world hunger? Me neither. And If we engaged in a modest conservation program in our gasoline use and gave the saved grain to the hungry, no one would have to go hungry, at least for the moment The feed use is increasingly for beef, and the fuel use is primarily bioethanol – an attempt to use the “cushion” in world grain production to let the middle class, particularly in the

US and China, indulge in quarter-pounders and gas guzzlers for a few more years, while the poor’s burgeoning undernourished try to maintain themselves on an ever-slimmer portion of the grain production.

Feed and fuel compete with food not only for consumers, but for land. The EU has adopted a policy requiring 17% of its farmland to be devoted to biofuels in place of food.29 Land from Brazilian deforestation (which of course many of us would rather see not at all) could produce grain for food, could support range cattle, or could produce sugar cane (or grain) for ethanol. Not surprisingly, biofuel and beef are Brazil’s primary products from destruction of the rainforest.30 Food comes out as a poor third in competition with feed and fuel both for grain and for land. No wonder there were riots over bread in 2008.

“THE MIX IN 2008 WAS 47% FOOD, 35% FODDER, 18% FUEL. THE 18% THAT WE BURN IS MORE THAN SUFFICIENT TO FILL THE STOMACHS OF THE RECORD 1 BILLION PEOPLE WHO ARE UNDERNOURISHED TODAY. DOES IT GIVE YOU A WARM AND FUZZY FEELING THAT WE BURN THE GRAIN THAT IS SUFFICIENT TO ELIMINATE WORLD HUNGER?”

And we have hardly looked at the inevitable consequences of an agriculture dependent for more than half its productivity on fossil fuels, outside the control of one-acre farmers in the Third World or even of thousand-acre farmers in the US. Two of the simpler ties between fossil fuels and food are the costs of fertilizer and water for a typical Third World one-acre farm. With most of the cost of fertilizer(although varying widely year-to-year and place-to-place, $100/acre is a reasonable figure) coming from the cost of natural gas, its cost is going to go up rapidly as oil runs out and (if it happens at all) as the world starts to do something about global warming. And the cost of gasoline at $3/gallon for pumping the water from an -all-too-typical 500-foot-deep well sufficient to irrigate an acre for a year is about $200.31 So rising fossil fuel costs are likely on the near term to drive up fertilizer and water coss by hundreds of dollars per acre The Ogallala-Aquifer farmer may be able to “pass the cost along to the consumer”(Brace yourselves, Americans!), but the farmer in India or China or Bangladesh has mostly to pass the cost on to herself. Where will it come from? Less fertilizer, less water, less food, with one billion people hungry already. These are of course just illustrative costs, but he writer suspects they are more accurate than the assumptions made by the U.N. Food and Agricultural Organization in its food supply projections for the next decade, that the international community will invest $200 billion per year for technological improvements in agriculture, that oil production will meet demand and that its costs will hardly budge.32 So even if the world can produce enough food, most folks may soon be unable to pay for enough.

The story of how we got here is complex – a confluence of population boom, oil boom and bust, the tragedy of the commons, misallocation of resources between rich and poor, the almost-deliberate blindness of America to the consequences of biofuel production -. the list goes on. There is an ongoing academic argument about whether the plight of the poor is one of inequitable distribution “or” population, but it is quite clear at this point that the answer is “Both.” There is also a sociological factor – the separation of people from the land, which has allowed us to “commoditize” land, to block the recycling of phosphorus and nitrogen, to separate sustenance from daily life, to warehouse in China’s cities the millions who had recently been attached for millenia to the cycles of sun and rain and soil. Out of sight, out of mind. We will not treat the earth sustainably when we do not see it and feel it in our daily lives and know directly that what surrounds us is what keeps us and our descendants alive and healthy.

There are too many of us to go “back to the land,” but we must preserve the connection. In coming decades necessity will dictate that everyone produce their own food wherever and however they can, but more important, we must reconnect ourselves to the earth we have abused. You who put aside a little corner of your urban homestead where things green can flourish are preserving the connection as best you can, and must teach others to do likewise. You are preserving an essential thread to our past, which will, if we are lucky, allow us to have a future.

But it’s a slim thread.

It didn’t need to be this way. Norman Borlaug, far from viewing himself as the man who proved the doomsayers wrong, knew what was coming if we didn’t take care. In his Nobel lecture he described the Green Revolution as giving the world a “breathing space” until the year 2000, but then referred to an “impending doom” imposed upon us by the “Population Monster ,” and told his audience that”the frightening power of human reproduction must also be curbed; otherwise the success of the green revolution will be ephemeral only.”

Dr. Borlaug said in his lecture that whether and how we deal with the population problem is a”test of the validity of “sapiens” as a species epithet.” We have so far failed the test and squandered the thirty years he gave us. But the substantial fraction of the grain crop not used directly as food can, if we act quickly, allow us without famine to put ourselves on a sustainable population track, one recognizing that we don’t presently feed ourselves and that on the present track, things will get much worse. And of course no technical fixes can give the bottom seventh of the world population the wherewithal to pay for what they eat, so the looming food crisis will not just be fixed with a theoretical food supply for which they cannot pay. These things must happen. Is that likely? Probably not, given past history. But it is necessary.

Once again we 6.9 billion people are on our own, without leaders or guidance. But we know what we must do, as individuals and nations: we must avoid gasohol and beef, because we cannot take food from the mouths of the hungry; we must manage and conserve our diminishing water supplies, we must work to eliminate abject poverty so that people can pay for what they eat and we must begin to decrease our numbers by limiting ourselves to one child per family.33 There is no evidence that we can avoid famine otherwise. The Green Revolution was a one shot deal, because we cannot again double irrigated acreage or multipy use of chemical fertilizers by five; and because the Green Revolution was a program of the oil age, which is fast departing. Modest crop-yield increases may keep up with population growth for a while (although they haven’t for 25 years), but all indications are that the prices of what food there is will rapidly climb above the budgets of billions of us.

“Norm Boy,” the Iowa farm kid, died last year. He was 95.

………………………………….

The writer is a California-licensed attorney currently residing in Massachusetts. He has had professional experience trying without success to implement groundwater management in California’s vast agricultural San Joaquin Valley. Research and writing were supported by Urban Garden Magazine, which reserves copyright and all other republishing rights except the right to online submissions by the author. He wishes to thank Patricia Lemon and David Steele for invaluable editorial assistance.

1. This article will be published by Urban Garden Magazine in mid-August.
2. Bruce Alberts, President, NationalAcademy of Sciences
3. For the full lyrics, see http://www.netstate.com/states/symb/song/ia_corn_song.htmor http://iowareunionclub.com/iowacornsong.aspx
4. Mark Yudof, President, University of Minnesota.
5. Biographical information from Vietmeyer, Borlaug, Volume 1 (2004), unless otherwise indicated..
6. Dr. Borlaug’s Nobel lecture: http://nobelprize.org/nobel_prizes/peace/laureates/1970/borlaug-lecture.html
7. See Dr. Thomas Stein, sakia.org, 2007, http://www.sakia.org/cms/fileadmin/content/irrig/general/stein_2007_water_use_charts-units_converted.pdf for a general compilation of different foods and their water needs for production, together with a link for explanations as to how these were determined.
8. See chart, Global Education Project, Food and Soil, http://www.theglobaleducationproject.org:80/earth/food-and-soil.php. A hectare, a 100-meter square, is 2.2 acres. Spend an hour studying these charts, and you will know more than the average Ph.D. about modern agriculture.
9. World Bank, Groundwater, http://web.worldbank.org/WBSITE/EXTERNAL/TOPICS/EXTWAT/0,,contentMDK:21633297~menuPK:4620525~pagePK:148956~piPK:216618~theSitePK:4602123,00.html.
10. (Garrett Hardin, 1968 paper published in the journal SCIENCE (162:12431248). If you aren’t familiar with it, read it, and then go for a vacation and meditate on it for a week.
11. Lester Brown, Aquifer Depletion, 2006, http://www.eoearth.org/article/Aquifer_depletion
12. Patricia Muir, http://people.oregonstate.edu/~muirp/waterlim.htm
13. UN Food and Agricultural Organization (FAO), Agricultural Outlook 20102019 (2010)
14. Lin Shujuan, China’s water deficit ‘will create food shortage’, Science and Development Network, 2007, http://www.scidev.net/en/news/china-s-water-deficit-will-create-food-shortage-.html; and Lester Brown, WATER DEFICITS GROWING IN MANY COUNTRIES: Water Shortages May Cause Food Shortages, http://www.greatlakesdirectory.org:80/zarticles/080902_water_shortages.htm.
15. T. V. Padma, Thirsty Indian farming depleting water resources, Science and Development Network, http://www.scidev.net/en/news/thirsty-indian-farming-depleting-water-resources.html, quoting scientists from NASA and also citing the Indian Ministry of Water Resources..
16. http://www.eoearth.org/article/Aquifer_depletion,
17. See e.g. the graphs shown in Staniford’s article cited below.
18. Patricia Muir, http://people.oregonstate.edu/~muirp/waterlim.htm
19. Stuart Staniford, Food to 2050, The Oil Drum, http://www.theoildrum.com/node/3702, discussing both sides of the dispute. See also Grain Production, http://www.whole-systems.org/grain.html, and Science’s February, 2010 issue devoted to food security. http://www.sciencemag.org/cgi/content/full/327/5967/812
20. Lester Brown, WATER DEFICITS GROWING IN MANY COUNTRIES: Water Shortages May Cause Food Shortages, above.
21. http://www.random-science-tools.com/chemistry/chemical_comp_of_body.htm
22. UN Food and Agricultural Organization (FAO), Current world fertilizer trends and outlook to 2011/12, Table 4, ftp://ftp.fao.org/agl/agll/docs/cwfto11.pdf
23. For a recent and very readable discussion of the phosphorus situation, see D.A. Vaccari, Phosphorus: A Looming Crisis, Scientific American June 2009, www.ScientifiAmerican.com.
24. Wikipedia, Fertilizers, http://en.wikipedia.org/wiki/Fertilizer.
25. GAO, Domestic Nitrogen Fertilizer Production Depends on Natural Gas Availability and Prices, 2003, http://www.gao.gov/new.items/d031148.pdf.
26. K. Bradsher and A. Martin, The Food Chain: Shortages Threaten Farmers’ Key Tool: Fertilizer, New York Times, http://bigteaparty.com/fertilizer-soaring-foodprices-key-to-health-bad-for-environment/
27. United Nations Environment Program (UNEP), Food from Animal Feed, World Food Supply, http://www.grida.no/publications/rr/food-crisis/page/3565.aspx). R. Segelkin, US could feed 800 million people with grain that livestock eat, Cornell ecologist advises animal scientists, Cornell University Science News, 1997, http://www.news.cornell.edu/releases/aug97/livestock.hrs.html.
28. Worldwatch Institute, Vital Signs, Grain Harvest Sets Record, But Supplies Still Tight, 2009, http://www.worldwatch.org/vs2009.. The UN Food and Agricultural Organization says the figure is only 9% for biofuels at this time, but also says that the amount of grain being turned to alcohol will double in the next decade. OECD-FAO, Agricultural Outlook 2010-2019. So if 18% isn’t correct today, then it is likely to be correct in a decade…
29. X. Navarro, The European Commission says no to reviewing biofuel percentage goal, http://green.autoblog.com/2008/04/15/the-european-commissionsays-no-to-reviewing-biofuel-percentage/
30. OECD-FAO, Agricultural Outlook 2010-2019.
31. 1 gallon [U.S.] of automotive gasoline = 97,181,192.2530305 foot pounds. 1 acre pumping from 500 ft.: 3 acre-feet of water = 975,000 gal water x8 lbs/gal x 500 ft = 3,900,000,000 ft lbs/ 97,181,192.2530305 ft lbs/gal gasoline = 40.131 gal x $3/gal = $120, assuming a 100% efficient pump, or $200 assuming a 60% efficient pump.
32. OECD-FAO, Agricultural Outlook 2010-2019
33. There is a time lag of 30-40 years built into any population policy based upon birth control, because a rapidly-growing population over-represents the age group under reproductive age. Consequently, a “ZPG” birth rate does not result in ZPG for decades. Moreover, the water and energy problems imply that an overall population reduction is necessary.

By Nicholas C. Arguimbau
31 July, 2010
Countercurrents.org

Well, we thought enough was enough. So we’ve put together this quick, no-nonsense and impartial guide to understanding how to measure the strength of your nutrient solution so we can all be clear about what we’re talking about – once and for all!

Worldwide, there is one standard parameter for measuring pH, but there are many more for measuring the strength of a nutrient solution. The two major measurements in use today are:

• EC  – Electrical Conductivity
• TDS – Total Dissolved Solids

EC

First, some basic concepts: when we add nutrients to water we create a nutrient solution. The more nutrients we add, the more concentrated the solution, and the more readily it will conduct electricity. So, the electrical conductivity (EC) of your nutrient solution can be seen as a quick and easy measure of how much nutrient is dissolved in it overall. Put another way, measuring the conductivity of a solution means measuring the electrically charged ions. Pure water will not conduct anything, but tap water already contains other minerals, metals and salts so it does conduct a small amount. Remember, it’s always important to measure your source water to see what you’re dealing with.
To measure conductivity we can use an EC meter, also known as a conductivity meter. It has two electrodes that, when dipped in the solution, measure its electrical charge by passing a small charge between them.

What is EC measured in?

Siemens are to “electrical conductivity” what feet or meters are to “length” – it’s the unit of electrical conductance. It’s important to get this distinction really clear in your head right now. EC is the scale (also known as the ‘parameter’) and siemens are the units. When dealing with the very low amounts of conductivity associated with EC in nutrient solutions, the preferred units are mS (millisiemens; one thousandth of a siemen) and µS (microsiemens, one millionth of a siemen) per centimeter.
EC is the most widely accepted measurement for the strength of nutrient solutions, and is the standard in Europe and many other parts of the world. The one notable exception is North America which prefers to use TDS.

TDS

TDS (Total Dissolved Solids) is the preferred scale for measuring the strength of a nutrient solution here in North America. It quantifies the concentration of dissolved solids contained in a solution. TDS is arguably a better parameter for measuring nutrient concentration, since it measures by quantity or weight.  In other words, you can have two glasses of water with equal parts TDS but different EC levels, since one glass may have more or less conductive elements (say salt vs. calcium.)
The problem is that a true TDS measurement is difficult to achieve (and would also defeat the purpose since evaporation is required).  Therefore, if one wants to eliminate the estimating that the conversion factor does, an EC meter is better.  If we lived in a perfect world, and every nutrient company and TDS meter used the same non-linear scale, a TDS meter is preferable.  But since there are so many different variables, an EC meter lends itself to more consistency.

What is TDS measured in?

Once again – make sure you get your head around this – TDS is a scale, or a parameter, just like time, length, temperature and volume. The unit of TDS is ppm (parts per million.) A TDS reading of 50 ppm means there are 50 milligrams of dissolved solids in each liter of water, or 50 mg/l.

How do TDS Meters work?

If EC meters (conductivity meters) work by measuring conductivity in a nutrient solution and expressing this in siemens, how to TDS meters work out how many parts of nutrient there are per million of water? Sorry to break it to you, but the answer is, they don’t.
TDS meters work in actually the same was as EC meters! Both measure the electrical conductivity of the nutrient solution they are dipped in. The difference is in how the information is displayed.
A TDS meter will measure the electrical conductivity, and then use a conversion factor to display the strength of the nutrient solution in ppms. Now here’s the slightly tricky bit. The conversion factor from EC to TDS varies from meter to meter.

Conversion Factors

TDS NaCl

NaCl is a conversion factor based on Sodium Chloride (regular table salt.)
The conversion factor range is 0.47 to 0.5.
Non-linear meters based on NaCl typically use: 0.5 x the EC level (if converting from µS to ppm or mS to ppt) or 500 x the EC level, if converting from mS to ppm.
TDS 442™

442™ or Natural Water™ is a proprietary scale based on properties of naturally occurring fresh water.  The 442™ part is an abbreviation of 40% sodium sulfate, 40% sodium bicarbonate, and 20% sodium chloride.
The conversion factor range is 0.65 to 0.85.
Non-linear meters based on 442™ typically use: 0.7 x the EC level (if converting from µS to ppm or mS to ppt) or 700 x the EC level, if converting from mS to ppm.

TDS KCl

KCl is a conversion factor based on Potassium Chloride.
The conversion factor range is 0.5 to 0.57.
Non-linear meters based on KCl typically use: 0.55 x the EC level if converting from µS to ppm or mS to ppt) or 700 x the EC level, if converting from mS to ppm.

TDS 640

A less popular conversion factor.
The conversion factor range is 0.64 to 0.67.
Non-linear meters based on 640 typically use: 0.64 x the EC level if converting from µS to ppm or mS to ppt) or 640 x the EC level, if converting from mS to ppm.

Yes, four different possible conversion factors means that four different meters that give measurements in ppm may all give different readings from the same solution! However, all EC meters should give the same reading in the same solution as there’s no conversion factor necessary.
I know, I know … TDS sounds like a confusing thing – but it’s really just a measure of the total ions in solution. For every gallon of water you have X mg’s of stuff in it. If one of your friends starts talking about their nutrient solution in terms of TDS, be sure to find out what scale they are using. Many growers, especially in Europe, in an effort to avoid confusion, use EC. If you are still confused, contact the manufacturer of your nutrients and find out what they recommend. Remember to ask them what TDS scale they use if they give you dosages in terms of ppm.
Likewise, if you are working with a TDS meter that only has a ppm display, remember you need to be sure of the conversion factor being used. TDS comes into its own when you need to measure individual elements in applications such as nutrient and water quality, tissue analysis results and soil analysis. Results from these laboratory tests will give individual elemental readings in ppm or mg/l. Remember, a TDS meter will only give you an approximation of the overall nutrient concentration, based on the conversation factor used.
Below is a table to show the relationship between the various methods of displaying the strength of a nutrient solution.

Jargon Buster

• EC = Electrical Conductivity
• TDS = Total Dissolved Solids
• PPM = Parts Per Million
PPT = Parts Per Thousand
• µS (or µS/cm) = micro-Siemens (one millionth of a siemen.)
• mS (or mS/cm) = milli-Siemens (one thousandth of a siemen.)
• NaCl = Sodium Chloride (EC-to-TDS conversion – EC x 0.5)
• KCl = Potassium Chloride (EC-to-TDS conversion EC x 0.55)
• 442 = 442 Natural Water™ (EC-to-TDS EC x 0.7)  (The “442” is an abbreviation for 40% sodium sulfate, 40% sodium bicarbonate and 20% sodium chloride.)

Making Sense of your Meter

Here are some popular TDS meters along with their conversion factors, where applicable.

Towards A Clearer World

There is a drive towards some standardization in the hydroponics industry to create less head work for all concerned. Nutrient manfacturers, if you specify dosage with in ppms, please also state what TDS scale you are using. This includes calibration fluid!

by Everest Fernandez

If ever there is a mountain made of a mole hill in the indoor gardening industry, where the logic of 1+1=3 is reasonable and ten products can be justified from two elements – I think bloom boosters fit the bill. In contrast to field-crop agriculture, horticultural nutrient companies often recommend combining base nutrients with various bloom boosters in the early, mid, and near-end of the flowering cycle. To the inquiring hobbyist grower redundancy can seem like an understatement since similar minerals are present in various boosters; and, in contrast, the science they’re founded on might seem as hypothetical as opinion when the grower seeks clarification on the reasoning behind their differences. In the end, to some, it seems surety is abandoned for a faith-based trust in nutrient companies to provide us with bigger, better, and more profitable yields. Are bloom boosters based on science or snake oil? Let’s take a look at a few products that hopefully serve to represent the numerous boosters available.

Turn the N knob to Low:

So the first thing you noticed is the mass majority of “boosters” have little or no nitrogen. Boosters are traditionally phosphorus and potassium at various ratios, and often a bit of other stuff like magnesium or sulfur. This is not the recent brain child of growers in Mendocino or B.C. but an older wisdom passed down from the agricultural field crop researchers from the 17th through to the 20th century. Early testing showed that soils with too little NPK, or lacking the conditions for availability of the elements, responded well to fertilization – and furthermore that too much nitrogen when the plant’s metabolism is shifting to reproduction delays the transition as the nitrogen induces vegetative growth. A trial published in 1951 further concluded that, though the reproductive stage requires a higher ratio of PK to N, without the nitrogen yields dropped over 50%. Because high-PK boosters are recommended for use in conjunction with regular nutrition, the general absence of nitrogen in the boosters serves to tip the scales while continuing to provide regular “base” nutrients.

Early bloom

Historically farmers would use sun-dials and count the hours of the day. Once the days became 14 hours or less the farmers would apply a hefty dose of phosphate and potassium, irrigating it in using bamboo shoots as tubing and a water wheel to pump the nutrient solution. They would mark their calendars “week 1″ and this would begin their “bloom chart” for the season. For real? No.

Looking into the “first week of bloom” booster phenomenon, and where it originated – and particularly some data to support the notion – has left me stumped. From what I can surmise the appearance of early bloom boosters originates many years ago with Rambridge’s Blossom Blood, which is to be used once the first flower or fruit is initiated. The premise is that a slightly-acidic nutrient solution promotes flower development, and the product holds the solution at a stable optimal pH. The label states it is a “selective pH control water treatment” and peripherally notes Monobasic Phosphate as an ingredient. This may entail a phosphate buffer as a mixture of K2HPO4 and KH2PO4 or maybe Na2HPO4 with citric acid – we can only guess. At just over $220 for 300g it’s certainly not an inexpensive ‘”buffer.”

Grotek, who produced the next generation of early bloom boosters, have included a fairly sizable PK into their flatteringly named Blossom Blaster. With an NPK of 0-39-25 this Grotek booster is used in weeks 1 and 3 with the allusion that an immediate alteration of the nutrient ratios will “contribute to proper plant maturation.” Blossom Blaster’s mainstay salt is monopotassium phosphate [MKP] and retails for around $240.00 for 500g.

Advanced Nutrients then marketed a similar “first week of bloom” booster called Bud Blood (bless their shamelessness, all of them) with the same NPK as Grotek’s. Bud Blood is derived from a few different source ingredients than competitive products and retails in the zone of $273.50 per 500g.

Alltek brand’s Flower Blood reinvents the 0-39-25 with the inclusion of Phloxine, a phytotoxic red dye alleged to stimulate leaf senescence, and Allantoin, a plant hormone present in plants during flowering and considered to induce or quicken the metabolic shift to bloom.

Other boosters used early in the bloom cycle include: Top Load, Dr. Node’s, Phosphoload, Megabud, et al. These products are sometimes used for controlling vertical growth or reducing the space between nodes in blooming plants – which can be ideal for indoor gardening in restricted spaces. Consideration should be made to ensure your chosen early bloom booster is appropriate for your crop demands; and, if required, that it meets criteria for human consumption.

Mid-Bloom

Years ago if a person ventured into using a bloom booster it would have likely been an 0-50-30, whereas, in recent times, that tendency has evolved into the confusing lower-NPK boosters and stimulants often packed with bio-active ingredient. The “old school” realm of 0-50-30 includes Grotek’s Monster Bloom (0-50-30), FHD’s Ton O Bud (0-49-42), Rambridge’s Monster Blood (0-50-30), and Advanced Nutrients’ Bloom Booster Pro. There is not only a commonality between these products’ stated mineral profiles, but as well of labelling – the Rambridge, Grotek, and Advanced Nutrients products all feature a reddish composite flower; Ton O Bud being unique in that regard. Prices are around $65 for 500g of the 0-50-30.

General Hydroponics’ Liquid Koolbloom (0-10-10), Canna’s PK 13/14, and competing Hammerhead PK 9/18 by Advanced Nutrients continue along the mineral path, each presumably delivering the perfect ratio of P and K to compliment the manufacturers’ respective base nutrient schedule. In the zone of $30 a liter these boosters are likely WYSIWYG – a safe bet to boost your plants without including hormones or other undeclared compounds which may or may not be proven safe and effective.

Among the bio-stimulant bloom boosters is Massive which claims “over 80 different organic compounds” and labels Gibberellins [GB] and Triacontanol [TRIA]. Oddly enough Massive also hosts a higher N percentage than P! GB are a much discussed plant hormone without a lot of data relative to its use with short-day annual plants, and though claims are made within hobbyist circles they are ambiguous. Numerous amateur trials have been conducted on GB to reproduce the dramatic cell elongation that caused it to be discovered initially in rice patties presuming it would deliver larger blooms, yet the tests are not entirely conclusive. TRIA is a plant hormone found in alfalfa (cuticula of various plants) and beeswax. When tested in nanomolar concentrations TRIA has shown to increase cell density, total chlorophyll, and drastically increase photosynthetic CO2 assimilation. Numerous articles on various plant species are available in scientific journals citing the benefits of TRIA, and rest assured Massive is not the only product which contains it; however debate still exists as to the plant-availability of TRIA without adequate solvency.

Listed as a “beneficial” but commonly considered a booster is Advanced Nutrients’ Big Bud (0-10-40 and 0-1-4 hydrated) which includes a hearty dose of magnesium as well as an assortment of L-amino acids. L-amino acids have been found to affect numerous plant processes from root development, protein synthesis, enhancing photosynthesis – as well as providing nutrients and improving the microbial conditions of the soil. During times of stress plants do not synthesize all L-amino acids, so Big Bud may make a suitable transplant nutrient in the right dilution.

Late Bloom

The repository of old feed charts speaks volumes about how much variability there is to late boosters. The base nutrients in each recipe are not identical, and though one may assume for simplicity that each recipe will, in the end, target a similar nutrient ratio, that is not necessarily the case. Without clear evidence of what might be “the best” the consumer is often left to chose a recipe based on gut instinct and advice from other growers.

Keepin’ it simple with the mineral salts is the time-tested Kool Bloom powder by General Hydroponics that appears fairly often in various recipes. Kool Bloom (previously Kabloom!), rockin’ the 2-45-28, comes in 2.2lb packs for only $45. Bustin’ out the Super Phosphate is Supernatural Brand’s Bud Blaster (1-52-31) used in conjunction with Super Boost (10-49-10) which is also garnished with a dash of B1. Super phosphate is not donned on a lot of labels making Bud Blaster a fairly unique and potent high-phosphate option at around $95 for 500g. A more recent addition to the late booster family is Overdrive (1-5-4) by Advanced Nutrients, which hosts a mineral profile quite similar to their 3-Part Bloom. “Overdrive” retails for around $39 per liter.

We can see a trend in high-PK boosters, leaning clearly towards the phosphates, but not all plant scientists agree that phosphorus is the key in final stages. Dr. K by Alltek is a hefty dose of potassium in its chloride form, and is claimed to be ‘designed to harden flowers at the ripening stage.’ ‘Muriate of Potash’, as it is also known, is a well utilized agricultural staple worldwide; and contrary to common presumptions the chloride is not reactive like chlorine and has not proven harmful to microbiology or roots. That said, in limited drainage situations chloride can accumulate and become toxic, so it is not often included in liquid nutrient formulas.

Finishing the late boosters is Green Planet’s “Finisher” which is the antithesis to the high-PK paradigm – as it contains none. Finisher’s ingredient includes ‘organic enzyme activators, vitamins, essential amino acids’ – aka The Other Stuff, including another dose of TRIA to spice things up. If the lack of PK bewilders you, I would get used to it. The bio-chem soup of barely pronounceable plant extracts and patented molecules is the way of tomorrow. If you understand and love your mineral salts, they will probably never disappear from the store shelves – but make way for the new generation of bloom boosters and stimulants that boggle the mind!

Previously: Grow Store 101: Base Nutes and Organic Enhancers
Next up: Grow Store 103 – Bennies and Bugs and Buffers (oh my!)

by Hydroguy

The hydroponics and indoor gardening industry is rapidly changing and evolving. Recently the pace of that change has become quite staggering with new products seeming to appear almost daily – nowhere is this more prominent than in the field of plant nutrition. In the last few years the hydroponic nutrient market has progressed from offering base nutrients and some phosphorus flowering boosters through to today’s market where a staggering (some might say ‘bewildering’) array of new technologies and theories are promoted.
Two product types that have been causing a lot of chatter in the growing community are carbohydrate (sugar) supplements and amino acid based additives. And for good reason. Sugars and amino acids are both interesting concepts in the context of plant nutrition and many experts consider them to be on the cutting edge. All sounds pretty exciting doesn’t it? But before you rush off and buy that next fancy-labelled bottle of sugary or amino acid goodness, you really should get your head around some basic facts concerning these substances and the ability of plants to make use of them.

Carbohydrates – Are They Really ‘Candy’ For Your Plants?

You’ve probably heard the hype about carbs: “Feed your plants supplemental carbs and turn them into Olympic Gold Medal winners!”
So a grower walks into their local store, decides to buy a big bottle of some sugary carb supplement, with the intention of deploying it on his next res change. The notion is that the plants will suck up the carbs and get a boost of ‘pure energy’ without having to go through the hassle of producing them as a product of photosynthesis.
Errrr, sorry to spoil the big carb party, but it’s not actually that straight forward. The carbohydrate supplement is definitely a case where theory got ahead of practice. In theory providing your plants with an array of simple and complex carbohydrates seems like a great idea. We all know that plants, driven by light energy and photosynthesis, produce sugar and starch.  The plant uses this for growth and development.  So the theory goes – if we supplement our nutrient solution with those very same sugars and starches, then the plant won’t have to make them all for itself and can therefore devote its energy to other things – such as making big flowers and fruits! Alternatively,  if the plant is undergoing a period of physical stress (such as flowering or fruiting) then the supplementation of those sugars and starches will enable the plant to grow and develop at warp speed as we have removed a limiting factor. Unfortunately all this seems feasible in a text book but, as usual, these things are rarely as simple in real life.
Why not? Well, put simply, it’s one thing to supplement a plant with carbs in a lab, quite another to do so in vivo (real life – real situation.) You can inject carbs directly into a stem or a leaf, for instance, using laboratory techniques, but surely the crunch question is: can a plant uptake carbohydrates through its roots? I have been involved in research that aimed to determine whether plants could actually uptake and utilize carbohydrates and, if so, what could they uptake and utilize. Carbohydrates range in size from very small, simple structures like glucose or fructose through to enormously large, complex molecules like polysaccharides.  So – did I find that plants could uptake simple and complex carbohydrates? Other than some very simple, and small carbohydrates (e.g. plain table sugar or fructose / glucose) plants essentially cannot take up other more complex carbohydrates through their root zone. Why?  It’s because of a unique little barrier in the roots called the Casparian strip – complete with his sidekick the endodermis. Essentially the Casparian strip forces everything, and that includes carbohydrates, through the endodermis to be actively selected or rejected for uptake.

Ready For The Science Bit? Introducing The Casparian Strip – Your Plant’s Very Own Homeland Security!

Inside the roots of your plants sits a very innocuous and extremely important band of cells – called the Casparian Strip. I like to think of this as a sort of “security guard” for your plant. It is used to block the passive flow of materials ( travelling between the cells), such as water and solutes into the main water carrying columns of the plant – the xylem and phloem. By doing this it forces everything to actively pass through or be rejected by the endodermis. Once within the epidermis, water passes through the cortex, mainly traveling between the cells. However, in order to enter the stele, it must pass through the cytoplasm of the cells of the endodermis. Once within the stele, water is free again to move between cells as well as through them. For solutes to pass through the endodermis they must be in inorganic, ionic form to be transported across to the stele.   As you can see getting water and nutrients inside your plants is no easy process!
An interesting side note for people who grow with organic nutrients.
When you hear of the virtues of organic fertilizers, remember that such materials are unable to meet any nutritional needs of the plant until they have been degraded / converted into inorganic forms. Organic matter does play an important role in making good soil texture and rhizosphere health, but it can only meet the nutritional needs of the plant to the extent that it can yield inorganic ions. Once within the epidermis, only the inorganic ions pass inward from cell to cell.

Amino Acid supplements and supplementation –  possible or possibilities?

Okay, after that bombshell, let’s take a look at Amino Acids. These are fascinating little things, these miniature building blocks of protein – body builders love them and, according to many growers, plants do too. So what roles do amino acids play in plant nutrition?

Table 1 shows the 21 Proteinogenic Amino Acids

There are total of 21 Amino Acids used in the production of protein and you’ve probably seen most of them listed on the back of a bottle by now. They are known as Proteinogenic Amino Acids

Every chemical reaction or process that goes on inside a plant relies on protein. From photosynthesis through to hormone production, growth and development, stress – proteins are used by the plant for every aspect of its life, so we can see that amino acids are very important in the big scheme of things.
This importance has not escaped the attention of researchers or manufacturers of plant nutrients and additives. We are now seeing quite a few emerging products that contain these essential building blocks of life. One area being examined by both researchers and manufacturers are amino acids that are direct precursors to hormones. Tryptophan is one popular amino acid being researched as it is the direct precursor to IAA -  a powerful growth hormone. Arginine is one of the precursors for cytokinins and is a major player in the production of flowers and fruits on a biochemical level.  Other exciting roles of amino acids include their part in mitigating plant stress.  Proline is produced by the plant in huge quantities during times of stress to assist with osmotic balance and to maintain a positive water status.
Amino acids are also used as a source of nitrogen in the root zone as they are delaminated by rhizosphere bacteria and fungi. The bacteria feed on the amino acids and in return nitrogen, in the form of ammonia, is released which can be absorbed by the plant. Ammonia is very rapidly absorbed and utilized by the plant and, in small quantities, is very beneficial to the support of rapid growth and development.
A new and very exciting and emerging area of amino acid research, and one that I am very actively involved in, is the role played by accumulated amino acids.  In plants, the roles of accumulated amino acids varies from acting as an osmolyte, the regulation of ion transport, modulating stomatal opening, and detoxification of heavy metals. Amino acids also affect the synthesis and activity of enzymes, and most excitingly of all play a major role in gene expression!
So it’s readily apparent why plant nutrient manufacturers would be interested in the humble amino acid – they could be very useful to growers!  As useful as might be, amino acids are also commonly misunderstood – just like the carbohydrates we looked at earlier. Once again theory is getting way in front of reality.
As with carbohydrates no one really looked at whether plants can take actively up amino acids through their roots. A major focus of my research is examining how or if plants can take up amino acids via their roots. One method is to feed plants a solution of radioactively labelled amino acids and then take special x-rays of the whole plant 24 hours later. You can actually visualize the extent of the amino acid uptake. In all of the experiments I’ve been involved in, almost none of the amino acid solution fed to the plants had been absorbed by the roots and transported to the leaves. So what’s at play here? Once again it’s the role of the Capsarian strip and endodermis coming into play and excluding the uptake of almost all of the amino acid solution fed to the plants. Amino acid supplementation does work to a minor extent – as some, but very few, of those root fed amino acids are absorbed by the plant. The exciting thing is that even that tiny amount that is absorbed positively affects the growth and development of plants.

So what did we learn?

Only simple sugars are absorbed by the plant root system. And only a very small amount of any amino acids supplied will ever be taken up by your plant’s root system. So what does that mean? Are carboyhydrate and amino acid producs a waste of your time? No – not exactly. Even when a small amount of amino acids are absorbed by the plant, we can get some positive effects. The simple sugars in your carbohydrate products do get absorbed. Others form a good source of food for beneficial bacteria in your root zone. So there are some benefits from using these types of products – just probably not to the degree that some of us may have hoped.
Feeding your plants carbohydrate and amino supplements is not a waste of your time or money – in fact many of those simple and complex carbohydrates serve as food for the friendly bacteria and fungi in your root zone. But don’t forget that your plant’s roots constantly exude simple and complex, carbohydrates, amino acids and proteins into the rhizospere and that those exudates serve as food and growth promoting compounds for many of the beneficial bacteria, fungi and micro organisms present in your plant’s rhizoshpere.
Root exudates are commonly divided into two classes. Low-molecular weight compounds –  such as amino acids, organic acids, sugars, and other secondary metabolites and high molecular weight exudates – such as mucilage (polysaccharides or complex carbs) and proteins. The rhizospheric bacteria and fungi return the favor, in a symbiotic relationship, by breaking down complex products in the rhizosphere into ionic forms the plant can absorb as well as excreting protein and secondary signalling molecules of their own that benefit the plant by increasing its rate of growth and development.
In fact, much or all of the apparent success of carbohydrate and amino acids products are due to this inadvertent power feeding of your root zone friendlies and the symbiotic benefits they return to your plants.

The Future of Carbohydrate and Amino Acids?

Biochemists and plant researchers around the world are conducting research into methods of delivering carbohydrates and or amino acids directly into the plant in large or precisely controlled amounts. We are conducting research on developing radical new delivery methods for compounds that are otherwise impossible to deliver to plants in a controlled or effective manner. Techniques such as bio and nano encapsulation technologies are currently being pursued and developed – the promise of these techniques is huge. They could allow things like complex carbohydrates and amino acids to be delivered to your plants as they need them.

As we’ve learned in part 1 and part 2, in order to grow successfully in a hydroponic system, there are certain basics that always need to be kept in check: otherwise, plant performance inevitably suffers. After covering source water, nutrient and pH, world-renowned hydroponics expert Michael Christan breaks down the final ingredients of a healthy indoor growing environment: oxygen, light, temperature, humidity, air circulation and CO2.

Photos courtesy of AmHydro.

The 5 basics of recirculation and plant performance:

1. Pure source water
2. Balanced nutrient ions/anions (EC)
3. Optimum pH
4. Plentiful oxygen availability
5. Optimum light/temp/humidity/air circulation/CO2

The Importance of Oxygen

It’s obvious that loose, friable soil with organic matter and thriving microbes grows plants much better than tight, clay soil devoid of organic matter. The primary missing ingredient in the latter is air (oxygen) availability.

The air we breathe is composed of gasses: 78% nitrogen (N2), 21% oxygen (02), 0.9% argon (Ar) and 0.03% carbon dioxide (CO2). The one we’re focusing on in this article is oxygen. The action of microbes on organic matter in a loose soil produces air pockets as organic matter is mineralized. These oxygen pockets are crucial to the survival and rapid colonization of healthy microbial populations. When the organic matter in the soil is fully consumed by the microbes and plants have consumed all the minerals, oxygen becomes depleted and, if more organic matter is not reapplied, plant performance slows and pathogenic (anaerobic) microbes can colonize. This condition is best avoided.

In media-based recirculating systems, the O2 is in the media: e.g. rockwool, perlite, grow rocks. Plentiful air space is available even after water is drained from the media. Roots thrive in O2-rich pockets. They are able to produce prolific root systems and plentiful root hairs to increase surface area to better absorb available ions. This is the best reason for using media with porosity. Of course, flood and drain systems suck fresh air into the media when it drains, which is why it’s such a great irrigation system.

In water-based recirculating systems, NFT, DFT and Aeroponics, O2 availability is intrinsic to the design of the system. NFT is a flat-bottomed tube with a shallow nutrient stream moving slowly, keeping root hairs moist and absorbing O2 (see “NFT Gro-Tanks,” UGM009). Aeroponics is misting droplets of water, increasing the surface area many-fold for roots to grow prolific root hairs for ion absorption. It supersaturates the solution with O2. DFT uses air pumps and water temp to keep roots bubbled with 02 and oxygen rich.

The heart of a media-based or water-based recirculating system is the nutrient reservoir. This too requires oxygenation, especially when water temperatures rise. The use of air pumps and air stones on smaller reservoirs and pump-powered eductors (venturis) on larger reservoirs make a big difference in pathogen suppression (nasty fungi and bacteria don’t like O2). This agitation drives ethylene gas from the solution and increases the longevity of the nutrient. Be sure that, if there are reservoir lids, there’s room for air exchange with ambient air in the room or greenhouse. Many commercial growers use fresh outside air in their eductors to keep the nutrient solution optimum.

Dissolved Oxygen (DO) can be measured to determine solubility of oxygen in fresh water. Fresh water at 72°F (22°C) has a DO of 8.7 ppm; at 82°F (28°C) it drops to 8.1 ppm. Salt solutions are lower. As a rule of thumb, every increase of 1ppm in DO is equivalent to an 11°F (12°C) temp drop. The cooler the temp, the higher the DO. You don’t want cold water on plant roots, though. You want 72°F (22°C) water at your roots for most plants.

When we measured DO in our greenhouse reservoirs, we found that a 74°F (23°C) nutrient tank at an EC of 2 had a DO of 6.3 ppm (low because of salts and sitting still). When we turned on an eductor (venturi), which we do in ALL reservoirs, we received a reading of 7.6 ppm. BIG difference. That’s an increase of 1.3 ppm without changing temperature.

Then we add an in-line Mazzei injector in between the tank and the feeder pipe, which raises DO to 8.3 ppm. By the time the water had run down the NFT channel and 18 plants had their way with the O2, with some off-gassing occurring, there was an 8.1 ppm DO left in the nutrient solution going back to the reservoir. That’s what we’re after! Plants thrive at those DO levels. Makes ALL the difference.

Be careful: as water temperatures of salt solutions increase, you must mitigate by adding O2 in the reservoir as well as directly on the roots. If you can’t get the DO level up by mechanical means, then you will most likely require a water chiller, which is expensive but sometimes imperative. If you cannot bring water temps down or increase DO in the nutrient solution, your next action will be disease suppression or inoculating roots with beneficials to out-compete the pathogens that thrive in high temp, low DO water. If you do get a DO meter, get a good one. We use an Extech Model 407510.

Light

Photosynthetically Active Radiation (PAR) light is a fancy term for the wavelengths plants use to vibrate chloroplasts to power the engine of photosynthesis, a vaguely understood process in my opinion. It is said that PAR light is in the 400 to 700 nanometer wavelength range. No big deal if you’re outside or in a well-lit greenhouse. But if you are growing under HID light or using it as a supplement, it certainly is.

Color temperatures of lamps are measured in degrees Kelvin from a color rendering index (CRI). The blue/white side of the spectrum has higher Kelvin temp: 6000K-8000K (MH lamps). The yellow/red side of the spectrum has lower Kelvin temperature: 3000K (HPS lamps). As a rule, the higher the Kelvin temp, the more vegetative the growth. The lower Kelvin temps are used for supplemental and/or flowering light. Different bulbs have different combinations or blends of gasses for better PAR value. Plants can be finicky and prefer one blend of light more than another. Trial and error, sometimes, is the only way to find out what your plants really like.

High Intensity Discharge (HID) lamps produce light when the gases inside the fused alumina tube are heated to the point of evaporation by high voltage electricity. This process forces the metal gasses to throw off a barrage of photons partly in the PAR range. As the bulb burns over time, the metal gasses slowly change form and degrade out of the PAR range. It is not obvious, but plant performance can suffer from lack of the PAR light when there is no shortage of photons to the naked eye. To look at light as a possible limiting factor, keep track of the hours your bulbs have been burning. If you are over the recommended burn range as stated by the manufacturer, that could be what’s compromising your system. Rule of thumb with HPS bulbs is to replace them every 12 months, and MH bulbs every 9 months, with HPS burning 12 hour days, MH burning 18 hour days.

Outside it’s obvious what limits light, like trees. But in greenhouses, if the glazing is dirty, that’s a big deal and that situation just creeps up on you. Depending on what you’re growing and what time of year it is, a dirty film can cut out as much as 30% of available light. If you are using an 85% transmission film and have 30% attributed to dirt, that’s 55%, basically shade cloth. In situations where there is too much light and plants are unable to cope with the leaf temperatures or solar radiation, a white or metallic shade cloth is preferable to black, as black can radiate heat back down on the plant canopy. A simple mistake easily avoided by many growers in double poly greenhouses is that the inflation fan is pulling inside air in between the films, thereby creating moisture that blocks light. You can tell by the droplets in between the films, or a haze. It is always recommended to use outside air for inflation. Of course, all of this is dependent on location, latitude, geography, plant in cultivation and skill/experience of the grower. We cannot cover all those variables in a brief article.

Temperature

Plant response to temperature is pretty obvious. It’s visible. Plants stop growing when root temps hit 58°F (14°C). Air temp can actually be cooler than 58°F, but when roots are cool, growth slows and stops even when air temp increases. When temps are too high, say 95°F (35°C) plus, depending on RH, air flow, light, kind, size, and age of a plant, they may stop feeding and spend their energy evaporating water from their stomata to cool down. Temperature must be managed to keep plants transpiring and active in the sweet spot.

Most temp controllers are effective, turning on fans for increased air exchanges, but when temps are too hot outside, air conditioners must be used. As a variable, though, temperature control is straightforward. It’s common knowledge that insects like very consistent temperatures and no air movement. Find which temperatures are your best high and low, and vary them morning, daytime and night. Keep an inhospitable environment for the pests without sacrificing plant performance: another dance to master.

Humidity

The two ways of explaining humidity are relative humidity (RH) and vapor pressure deficit (VPD). Most people are familiar with RH and use hygrometers so, for the purposes of this article, I will use RH.

In my experience, this is the one variable that most growers need to be more aware of. The dance between temp/humidity directly affects transpiration rates as poor transpiration opens the plant organism to disease and mineral deficiencies.

RH is the amount of water vapor present in the air expressed as a % of the amount needed for saturation at the same temperature. Here’s what that means: if the humidity is too high, e.g. 95% at 75°F, plants cannot transpire or evaporate enough water to pull minerals up the vascular system even with stomata wide open. This usually results in calcium (Ca) deficiency (remember, Ca is a non-mobile element and must be constantly supplied to growing tips) and plant stress, which increases their vulnerability to fungal intrusion.

If humidity is too low, 50% at 75°F, stomata will open in an attempt to evaporate water because of the low pressure around the leaf, but then close up to conserve cell pressure in the leaf. Plants stress as they cannot take in CO2 with closed stomata and growth stops as the plant is just trying to survive without going into wilt (i.e. loss of leaf turgidity from which it’s difficult to recover). Again the plant is vulnerable to disease and insects. These two extremes points will create a high probability of crop loss.

As a rule, at 75°F (24°C), if RH is below 60% you must add moisture to get to 75% (which is ideal), but stay below 85% to avoid stress and disease. At 85°F (29°C), if RH is below 70% you must add moisture to get to 80% (which is ideal), but stay below 90% to avoid stress and disease. As temperature rises, air holds less moisture. Steer your plants within these parameters for optimum plant performance.

When RH is too low, use a fogger or humidifier coupled with outside air exchanges. When outside air is too warm and dry, you will have to use some form of air conditioner (if that is the only way) to drop the temperature to increase the moisture-holding capacity of the air.

When RH is too high, raise temperature to reduce moisture saturation of air coupled with outside air exchanges. If outside air has too high of an RH, you will need a dehumidifier to pull water out of the air.

Transpiration is king. Monitoring transpiration rates and keeping them optimum with temp/RH manipulation is crucial. If you are outside of the temp/RH safe zones and don’t use some mechanical method of bringing them under control, you will always be fighting the results of that variable being unchecked. This is where high quality environmental controllers come in handy

You can buy the most expensive nutrients, goodies and gadgets available to grow your crop, but if your plants are unable to transpire and you don’t know that, you had best learn quickly or get a day job

Air Circulation and CO2

No matter what kind of controlled environment you’re running, greenhouse or greenroom, air circulation is another key component that is often overlooked until mildew takes out your crop or your plants starve from lack of CO2. The great outdoors takes care of all this, but inside you have to provide the controls or fall prey to what you didn’t know you didn’t know.

Rule of thumb: 60 air exchanges per hour. Not only do you need to flutter your plants with gentle breezes from an oscillating fan or horizontal air flow (HAF) fans in a greenhouse, but you must freshen the air with air exchanges from outside, taking advantage of the 385 ppm ambient CO2. The raw materials that PAR light makes into carbohydrates are CO2 and H2O. CO2 furnishes the carbon and oxygen, while water furnishes the hydrogen for the carbohydrate (CH2O).

If air exchanges are frequent, 385 ppm CO2 is plenty unless you’re looking to accelerate growth by enriching your space with higher levels to, say, 1500 ppm CO2. Even if you are adding CO2, you still must exchange air. There are numerous ways to provide CO2: chemical reactions, gas bottles, gas generators and a variety of controllers and monitors depending on the size of the operation. For the purpose of this article, you just need to know that it is a basic component of the indoor growing environment, and be mindful that it’s always available. Without CO2, plants will not grow.

One of my teachers, Grenville Stocker in NZ, took me into one of his client’s lettuce/herb greenhouses and asked me, “Would you get a chair, sit down, read a book or hang out in here all day?” Actually, it was way too moist, not enough air movement, my shirt was sticky, and it was uncomfortably warm. I said, “No way.” He remarked, “How do you think those plants feel? The same way, I reckon, except they can’t leave.” Then he showed me powdery mildew in certain areas, a thrip infestation and tip burn in some of the lettuces. The plants did not look vital, they looked stressed. I noticed the HAF fans were down, because of a blown breaker that the grower had been meaning to fix for a week. He had an RH monitor but no controller to check humidity and spill air or add heat … AND he was doing only 1 air exchange per hour because it was cold outside. He wanted to keep temps up inside without turning on the heat, which would cost him money. I looked at the RH: it was 95%. Temp was 80°F but it felt like 90°F because of the humidity. His client was too busy to pay attention or take coaching, and he wasn’t even there. Grenville always tested me; he’d say, “What’s wrong with this picture?” Then he would point out a basic that was obvious once I saw it. Most problems were easy to correct once distinguished.

I found out later the grower lost 50% of his crop and the other 50% was barely marketable. Had he kept HAF fans working, increased his air exchanges and turned up the heat to drive off the humidity with the help of a controller, he would not have had crop and financial loss. Just that one error cost him a market: he couldn’t deliver, so a competitor moved in. The point I’m making is: don’t leave your plants in an environment you can’t handle being in yourself. Use meters and controllers, but always keep them honest by paying attention to what your skin says.

All the variables of light, temperature, humidity, air circulation and CO2 must dance together in a harmony that you must monitor and control to be successful and avoid crop loss. If you cannot distinguish which variable is out, you will be guessing what the problem is and perhaps taking actions that are detrimental. Next time a problem arises (which inevitably will happen) and you’re scratching your head as to what to do, go through this list and check off each one that you KNOW is in tolerance. These 5 basics could be what you didn’t know you didn’t know. Now that you do, dissect them and become competent with each one:

The 5 basics of recirculation and plant performance:

1. Pure source water
2. Balanced nutrient ions/anions (EC)
3. Optimum pH
4. Plentiful oxygen availability
5. Optimum light/temp/humidity/air circulation/CO2

For the content and experiences that allowed me to write these articles, I’d like to thank my teachers, Grenville Stocker (Stocker Hort), Jeff Broad (AutoGrow), Genaro Calabrese (ex partner), Grant Creevey (Accent Hydro) and all our clients and associates for sharing and being open to “figuring it out.” Controlled environment plant cultivation is infinitely beguiling; I am always learning a greater respect for being part of that process. Genaro’s motto: “Every plant, every day.”

Good luck and good growing.

Michael Christian, the president of American Hydroponics since 1984, is a hydroponic system designer and consultant to commercial growers worldwide.

The basics – What is NFT?

NFT stands for Nutrient Film Technique. With this hydroponic system, plants grow in a purpose-built sloping channel with a fall of 1:40–1:50. Nutrient solution is pumped from a reservoir onto the channel where it passes over the plants’ roots and finally returns back to the reservoir. The roots on the channel develop to form a mat, which is partially in the shallow film of re-circulated nutrient solution, and partially above it. Utilizing this technique, the root mat growing in the nutrient film is supplied with essential water and nutrients, and the root mat above the film remain sufficiently moist with an abundance of oxygen.

The NFT system was developed between the 1960s and ’70s by Dr. Allen Cooper at the Glasshouse Crops Institute in the UK. In the early days, the growing channels were made in concrete floors. Today, growing channels are made from plastic and are often referred to as “trays” or “gullies.”

Why choose NFT?

Other than supplying your plants with the ideal root environment, NFT systems are incredibly efficient and environmentally friendly. The nutrient solution is recirculated for long periods: in some commercial applications, for many months. This continual recycling of the solution makes the most out of the water and nutrients you’re supplying. NFT systems also use very little growing media: just the small amount of substrate the plant is propagated in. This means that after each crop all you have to dispose of is a mat of roots, which easily biodegrades.

NFT Gro-Tanks

The system I will be demonstrating is called a Gro-Tank and is manufactured in the UK by Nutriculture.

The Gro-Tank is great for small-scale production as it has a wide top tray for the roots to grow on, with the reservoir directly beneath it spanning its whole length. A small submersible pump in the reservoir delivers nutrient solution to the tray above, which flows down the tray and back into the reservoir. This compact, self-contained design eliminates the need for lots of pipe work and is very low to the floor, making best use of the height available for tall/vining plants.

I have used the Gro-Tanks for many types of crops, including lettuce, basil, watercress, coriander, parsley, rocket, chard, chives, tomatoes, peppers, chillies, strawberries, cantaloupe melons, cape gooseberries, and many more. The diary below shows one of my NFT grows with cucumbers. I hope you enjoy…

Equipment

1 x heated greenhouse
1 x heated propagator
5 x starter plugs
5 x 4” rockwool blocks
1 x 604 Nutriculture Gro-Tank: 5ft x 1.5ft (153cm x 49cm) tray with 16 gallon (60L) reservior
1 x submersible adjustable pump
1 x submersible water heater
Spreader mat (capillary matting)
4 x roller hooks (plant supports)
Vine clips
Liquid nutrients and growth supplements

January 18th – Germination

I’m growing a cucumber variety called Carmen, which is an all-female F1 hybrid variety. The majority of cucumber varieties produce both male and female flowers; all we are interested in are the female flowers, as these develop cucumber fruit. This all-female (parthenocarpic) variety will develop a seedless fruit without the need for pollination. I found Carmen great last year for greenhouse growing as you don’t have to pick male flowers off and it produces large, full fruits.

I planted the seeds in starter plugs pre-soaked with a low-strength nutrient solution (EC 1.2) designed for seedlings and cuttings, and a liquid beneficial microbe additive. These were placed in a heated propagator and germination was fast!

Shown here is one cucumber seedling 8 days after planting. At this point they were transplanted into 4” rockwool blocks.

January 31st – Propagation

Considering it’s been 21 days since I planted the seeds, I’m happy with the way they’re progressing. They are now being watered with nutrient solution (EC 1.4, pH 5.8) every 2-3 days. The roots are doing really well and can be seen on the top of the block.

Without the block covers, algae would be taking over and the roots would not be growing so well on the surface. The natural light entering the greenhouse is being supplemented with 220W fluorescent strip lights. These plants should be ready for their NFT system in about 1 week.

February 4th – Growing on

The plants now need nutrient solution every day and the roots are clearly visible all over the bottom of the block. I also have increased the EC to 1.6. They will need to be planted in the next few days.

February 5th – Setting up

These cucumber plants are now 26 days old and are ready to go onto their final system, which will be an NFT Gro-Tank.

The most important thing about getting plants ready for NFT systems is to ensure they are well-established and have a mass of healthy white roots. Without this mass of roots inside the rockwool block, the plant will not be able to cope with the continuous irrigation of the NFT system. These plants have been propagated using an air pruning technique (see “Power Propagation” UGM0005) to ensure the rockwool block is packed full of roots.

This is the Gro-tank I will be using (below). It is called a 604. Nutriculture, which makes the system, also makes 5 other size variations to suit any grow area. The top tray is where the plants are placed and the reservoir underneath stores 16 gallons (60L) of nutrient solution.

The Gro-Tank has one delivery tube where the nutrient solution is pumped onto the tray using a small submersible pump with an adjustable output:

To ensure an even distribution of nutrient solution on the tray, I use capillary matting, aka “spreader mat.” The system manufacturers recommend using spreader mat and supply it with the system. One layer is enough. After laying it out, I fill the reservoir with water that has been standing in a storage tank for a few days: this allows some chlorine to be evaporated and, more importantly, allows the temperature to rise. Tap water in February in the North of England usually comes out ice cold and will seriously stress plants if used.

Once the tank is filled I turned the pump on and slow the output down so the solution lands in the middle of the first diamond. This provides a flow rate of approximately 1 quart (1L) per minute. Recommended flow rate for NFT systems can be anywhere between 13.5oz to 2 quarts (400ml to 2L) per minute. Determining flow rate in NFT systems usually depends on channel length; if you have very long channel lengths you will need larger flow rates. You could probably write a thesis on other variables that will determine the required flow rate for NFT, but I find that as long as nutrient solution flows as a shallow film and does not “puddle,” the plants grow well.

After a few minutes of the pump running, the spreader mat wets throughout the tray. I always run the pump and observe the way the water is flowing down the tray. I have found from experience that if the Gro-Tank is not placed on a level floor then some areas of the tray will develop puddles and other parts will remain dry. Leveling out the tank with thin pieces of plywood usually sorts out an uneven floor. Luckily, the floor is fine and I’m happy to “go with the flow.”

Now that I know the flow down the tray is perfect, I cut out the planting holes in the corriboard cover. Corriboard is twin-walled, semi-rigid plastic sheeting. It prevents any light from reaching the roots and can help provide a bit of support for the plants. I’m planting 4 plants in the Gro-Tank, so I cut the holes accordingly.

Providing support for large plants is very important. To support my cucumber plants I use roller hooks, which are a spool of string on a wheel attached to a support hook. The vines are trained up the string with the help of plastic vine clips. When they grow tall enough to reach the wheel, string is let out, which lowers the vine. This support hook is then moved along so the excess vine at the bottom rests on the corriboard. Using this technique, one of my cucumber plants last year was 49 feet (15m) long!

Another popular way to support plants on NFT systems is using netting, which is stretched out horizontally on a frame above the plants so that when they grow into it they are supported by the net.

Before planting onto the tray I remove the plastic wrapper from around the block. When I was learning how to grow using NFT systems I was told by a more experience grower at the time to “leave the wrapper on, otherwise the block will fall apart.” After a few crops I decided to experiment so I slid the wrapper up the block exposing the bottom third. This helped with initial establishment and root growth from the block, which I believed was a factor in achieving a more successful crop. The next crop I decided to risk it and remove the wrapper completely and, instead of the block falling apart, I got quicker establishment and a much better root mat. The block lasted the whole season, staying completely intact. Not surprisingly, I don’t follow this grower’s advice anymore.

Once the roller hooks are in place, I tie the string around the rockwool blocks and place them into position:

The positioning of the blocks on the tray is fairly important: I find staggering the plants works best. This allows the nutrient solution to flow uninterrupted through the mid-section of the tray, which helps once the root mat has built up. I also find that positioning the blocks so that the solution can flow through the grooves on the bottom of the block helps with establishment.

Then I place the corriboard and black and white sheeting back on the tray and lower the plants into their pre-cut holes. I cut the black and white with an X so the folds can be repositioned over the top of the block to cover it and prevent algae growth.

Now that the plants are in their system, I add a “grow” nutrient to the water in the reservoir at an EC of 1.6 and a pH of 5.8. I also add a strong dose of beneficial microbes to the mix to aid with root growth and disease prevention.

I put a submersible water heater in the tank and set the thermostat to 64°F (18°C). I also plugged in the pump, which I will now leave alone to run 24/7. Some growers plug their NFT pumps into a segmental or interval timer. This “pulse feeding” is not the strategy Dr. Allen Cooper conceived when he developed NFT, but some people growing plants with more sensitive root systems or who use large propagation blocks find it helps. It’s very important when implementing pulse feeding that the root mat never approaches a dry state. I have contacted Nutriculture about pulse feeding, and they only recommend that the pump is run 24/7.

These cucumber plants should settle in and start growing vigorously in the next few days. Hopefully I should be picking my first fruits in no time.

February 14th – Vegetative Progress

In 11 days these cucumbers on the NFT Gro-Tank have more than doubled in height and they are establishing well into their system. I have attached them to the string using plastic vine clips, which clip onto the string and hold the vine in place.

I have been routinely checking the nutrient solution pH and EC every 1-2 days. The pH was rising by 0.2 points every 2-3 days. As the pH reached 6.2-6.4, I added phosphoric acid to bring it back to 5.6-5.8. I like to let the pH drift a bit rather than keeping it within a tight range: as long as it doesn’t go higher than 6.5 or lower than 5.5, I’m not worried.

Usually I find the nutrient strength stays stable or increases slightly as the water level drops, but over the past 11 days the plants have used approximately 4 gallons (15L) of nutrient solution and the EC has dropped to 1.2. This is an indication that the plants are hungry, so I top up the reservoir with water and increase the nutrient strength to an EC of 1.8. Whenever I add anything to the tank I disconnect the delivery tube from the tray and submerse a larger 265 gallons/hour (1000L/hour) pump in the reservoir to mix the solution. Once the nutrient solution is corrected, I reconnect the delivery tube.

I always estimate how much water I add back to the tank and take a mental note. Once I know I’ve added back roughly the same volume as the tank holds (16 gallons / 60L) I will consider running the reservoir down to half full, emptying the tank, and refilling it with fresh water and nutrient solution.

Many growers change out the nutrient solution every week, regardless of how much the plants are using. I find this a bit unnecessary and like to base my solution change-outs on how the plants are using it.

The pictures below show how well the roots are extending from the rockwool blocks. Soon there will be a thick mat of roots all over the tray:

February 25th – Flowers and Fruits

It always amazes me how fast plants grow in a productive environment using hydroponic systems, but cucumbers are a whole other ball game. In 11 days they have more than tripled in size and burst into flower. One fruit is already quiet large and will be ready in a few days.

They have also started sending out tendrils and growing side shoots. I remove both but keep a few side shoots for cutting material and put them in my aeroponic propagator.

The greenhouse environment is pretty easy to maintain this time of year. The heating keeps the night-time temperature around 64°F (18°C) and the top vents ensure the day temp does not exceed 77°F (25°C). I have 2 centrifugal humidifiers running to keep the relative humidity between 60-70%.

The plants are now using 1.5-2 gallons (6-8L) of nutrient solution per day and I make sure I top up the reservoir frequently. It’s better to have a full tank as it provides a better buffer for changes in pH and EC. The plants seem happy with the nutrients at 1.8 EC so I’ll leave things be.

One thing I love about NFT is that you don’t have to think about irrigations. The pump is on a slow trickle, and that’s all that matters.

The cucumber fruit develops behind the un-pollinated female flower.

February 27th – Nutrient tweaking

We have had a few warmer, brighter days recently and the plants are loving it. The first large fruit is growing well but is showing signs that I need to tweak the nutrient slightly. You may notice in the picture below that the bottom of the cucumber is slightly more bulbous than the top. The leaves of the plants are also showing a faint yellowing (chlorosis) around the edges. This is a sign that the plant requires more potassium.

To increase the potassium in the solution I add a blooming additive high in potassium and phosphorus at the rate of 1 ml per L. Before adding this I top up the tank with water, add the PK booster, then add more base nutrient to bring it back to 1.8.

You may also notice some loose vermiculite on the tank and floor. I have introduced the predatory insects Phytoseiulus persimilis, which come in a vermiculite carrier. I noticed a small outbreak of spider mite on some peppers on the other side of the greenhouse, so as a precaution I sprayed all the plants in the greenhouse with a natural-contact insecticide that works by suffocation, not chemicals. A few days after spraying, I introduced the predators to clean up any lingering spider mites. I will now introduce a bottle of 2000 Phytoseiulus persimilis every 4 weeks throughout the greenhouse and keep spraying to a minimum.

February 29th – Roots going mad

The roots are really growing well now and starting to develop to form a mat in places. I like to regularly inspect the roots in the NFT system, mainly because you don’t get to do it with other systems!

March 3rd – Plant Training

The plants have now reached the full height of the greenhouse so I let out a small amount of string and lower the vines.

Once I have lowered these a few times I will move the roller hooks clockwise around the Gro-Tank. The stems rest on top of the corriboard. I started using this training technique with my tomatoes and tried it with cucumbers. I find it works pretty well but most commercial growers implement an umbrella training system. I have yet to try it but will get around to it one day.

March 11th – New plants!

The side shoots I took off 2 weeks ago are now rooted plants and are ready for transplanting.

I have to say, aeroponic propagators are great. I have one running continuously in the corner of my greenhouse and just put shoots in and forget about them. 1-2 weeks later you have cuttings. Can’t get any easier.

March 14th – The Bumper Crop

The plants have definitely responded well to the PK booster. The leaves are now dark green all over and the fruits have developed to be large, full and evenly shaped. Some are slightly curved but it adds to the character!

I’ve had 3 cucumbers off the plants so far, but today I picked 6 ripe fruits in one go. From here on out I guarantee I will have so many cucumbers that I will make myself and all my friends sick of the sight of them!

March 26th – Growing on

The cucumbers have been growing well and are now producing ripe fruit at a steady rate of two to three cucumbers every four days. They could try and produce more but I remove developing fruits once there are more than 4 developing on each vine. If there is a high fruit load on the plant, developing fruits will abort. The weather is starting to warm up and the greenhouse is now thriving from the increased day lengths and light intensity. Bring on summer!

Looking Ahead

Recognizing the environmental conditions and adjusting the nutrient solution is part of my ongoing management strategy for recirculating systems. As warmer weather comes along in May and June I will certainly see the EC rising every few days in the reservoir. As this starts to happen I will dilute the EC slightly to around 1.6.to compensate.

Water uptake will certainly go up too so I will have to make sure I regularly top up the reservoir once a day. I also make sure I service my pump every 2 months. This is fairly quick and easy to do and will give me peace of mind that it’s in good working order.

Interested in NFT and want to learn more? If you missed Everest’s introduction to NFT and grower’s tips in UGM0009, check it out here!

WORDS: Hydroguy

To all the consumers who find the sheer magnitude of the plethora of plant products bewildering: I feel your pain. To know nothing is sheer abysmal confusion, yet to know more does not seem to make product choice easier. When I see new growers walk into a store with a blank gaze I can actually observe their mental processes block as the overwhelming, yet exciting, stimuli flashes at them from numerous brightly colored bottles. This blank gaze often turns into a mix of confusion and skepticism. Too often novice growers think in terms of ‘Is it real or BS?’ whereas they should really be asking: ‘Do I need this?’ All products are of use in some or another application, it’s just a matter of finding what’s useful to you.

Base Hydroponic Nutrients

All organisms are elemental and require elements to live. We can look at our “vitamin/mineral” requirements as humans and it’s a short list. Plants have a similar “short list” and science has determined that, in order to technically survive, plants must get hold of them. Nitrogen, Phosphorus, Potassium (NPK), micro nutrients, etc. So these are the base survival needs. But to think of this as the limit of an organism’s needs is obtuse, just as a human would not have a great life eating cardboard for calories and taking vitamins. That said, whether your concern is simply production or quality of produce, you will need a base nutrient to supply the required minerals for growth. In the near-imperceptible chain of causality that affects plants outdoors, you have covered the most basic rudimentary needs. To qualify as a “base nutrient” all that is required are the N, P, and K in whatever ratio and micro-nutrients in sufficient quantity for your plant. Base nutrients are similar, but not the same. To arrive at a base nutrient (20-20-20 for example) a company can use various elemental compounds in combination; different combinations can have more or less purity at achieving the target mineral balance, and impurities are associated elements unintended for the outcome, such as arsenic. Aside from the ‘backpacked’ impurities in lesser quality products, different companies also use various arrangements of elemental compounds: for example, Calcium Nitrate or Ammonium Nitrate (among others) to provide the nitrogen. Different-sourced ingredients, as well as the final ratio of minerals, will all have slight variance in end use – those exact differences can be discussed another time.

Hydroponic base nutrients come in liquid 3-part, 2-part, and powder forms (”Why pay for water?”, some growers ask.) What you want is determined by preference, budget, availability, and trend. Read, ask your fellow growers, and inquire at your store to see what is buzzing – most base hydroponic nutrients are usable in any medium regardless of name. “Three part” can mean “use all three parts in conjunction” at different dilutions for each stage, or it can have one Grow and one Bloom for those respective stages and a third bottle added during both. “Two part” is often two parts for Grow and two for Bloom: four bottles mischievously pretending to be two. “Single part” is the actual two-part system with a Grow and a Bloom, or something representing those stages such as 20-20-20 and 15-30-15, and single part is also where you will find the “slurry” concoctions of mineral-based nutes with organics included. The ‘mineral/organic slurry’ is of some benefit to peat users since they add some cation exchange capacity (to be discussed later) to the inert peat without going all hippy.

“Well, I am using coco, so I need some coco food.” No, you don’t. Get better quality coco or add some cal/mag. Old coir was crappier because people didn’t realize the importance of desalinating it thoroughly, or some unscrupulous companies took the cheap route. Most coco-specific nutrients and only slightly increased in cal/mag and sometimes lessened in nitrogen – big whoop. If you are 100%-coco always then maybe it suits you, but I don’t see the importance.

There’s also the new “premium” base nutrients out there with labels donning expensive jewelry etc – these are still new to date for confidence, but if you’re willing to pay the piper for a trial there is some good buzz about some of them. As plant food becomes more of an organic chemistry art, we swerve less out of simple minerals and more into proprietary compounds we cannot know of even if we think we might understand them. That said, there still remains a need for disclosure and I can’t hold it against anyone for leaning to products with some transparency – in their attempt to avoid competitive replication, nutrient companies tend to alienate the consumer from understanding what their product is. Similarly, replication is a concern for consumers: nobody wants to add the same thing twice, and “just use it” is simply not convincing.

Organic Base Nutrients and Enhancers

The French Paradox. If you’ve never heard of it, pause to Google, but this is one example of a pretty basic point: there are more beneficial compounds in our food than simply vitamins. After the basic mineralogical requirements to sustain life, there are all the other bazillion compounds to improve the quality of life or, in our case, quality of produce of whatever form. An apple can technically minimally exist, or an apple can be packed with flavor, vitamins, and The Other Stuff (technical term – TOS). TOS represents turpines, flavonoids, organic acids, and a long list of stuff we don’t care to know of but still want to derive the benefits of. I don’t think it’s scientifically accepted that adding compost, kelp, guano, or another manure will increase the bio-active chemistry in produce, but “foliar feeding” isn’t accepted (in Canada) either – so my crutch is simple time-tested anecdotal observation: including organics will improve the quality of the end produce, thus increasing its flavor, aroma, and TOS.

Organic base nutes have come a long way in the last few years – mostly in convincing people they are worthwhile. We thought plants ate dirt, then realized they ate minerals from dirt (or water) – now it seems the geeks have decided that even larger organic compounds can make their way into the plants, such as vitamins. As always, it will always take science much longer to prove what people have been doing successfully for thousands of years, and continue to do today in “less advanced” areas of the world. The challenge for growers in the petrol world has been to match the yield of mineral nutes, and this has been displayed by various growers in enough circles to be generally accepted. It is a matter of substrate reuse and nurture, knowing what to add when – I will save details, but suffice to say if it is something you’re interested in it’s much easier today than ever, but still comes with a new learning curve.

Organics in hydroponics systems is something people would have balked at years ago; now there are products designed for such use. Growers have tested all forms of thick, organic sludge in their systems and, as much as commonsense still rules regarding buildup, slime clogs, and sugar coating, with a bit of elbow grease and absence of emitters or spaghetti hose many systems can run with nutrients not at all designed to be used in water gardens. The rigidity in this case is for generalization: you can’t tell everyone to do something that half will screw up. But, given the motivation and some knowledge, all these “can and can not” principles of growing can be realized as arbitrary guidelines. Beyond the liability of warranty and labeling, do what thou wilt.

ENHANCERS are there to enhance mineral nutes. You see, I think organics makes quality, whether it’s true or not. What is less debated is the notion that organic enhancers help make mineral nutes more available. Cation Exchange Capacity (CEC) are big words meaning “the ability for dirt to grab nutrients for later use.” Peat has nearly none, coco has some – either way, more is good. Humates, composts, organic sludge – these are midway rest stops for minerals between your bucket and your plant because they have a high CEC. Without a CEC component in peat, your nutes are pretty much only around as long as they are soluble – or, with reactive minerals, much less time. Without organic stuff, peat is only a fiber: it hasn’t any real ability to stretch the lifespan of a mineral nute until an organic component is added. Often a combination of things are used, such as guano or worm castings added to the peat – and/or some compost tea or other organic blend (or even a dash of base nute sludge, gotta love the sludge) with food irrigated in.

Next Up: Grow Store 102 – Bloom Boosters and Stimulants

Hi, my name’s Everest and I’m from the future.
>> From which year Everest?
I’m also the president of the United States.
>> It’s an honor to meet you Mr. President.
And perpetual economic growth is a good thing for the planet too.
>> Hi ho, hi ho, it’s off to work I go…
Genetically modified foods are perfectly safe for human consumption.
>> Thanks for putting my mind at rest Mr. President.

Do you hear that? Silence. That’s right, there’s not even a murmur of dissent. Whatever you say, it seems, goes.

So, furnished with this knowledge, what’s your next move? Will you start your own global media empire? Or is it preferable to take a vow of silence?

One has to wonder what value any ‘truth’ would have in a world where words are so readily accepted as the real McCoy. And even if you were to confess your special powers of persuasion to the world via your dedicated 24-hour news channel, still the masses would faithfully accept every broadcast word as gospel. Tell them everything is fine. They believe you. Tell them everything isn’t fine but you can fix it for them. It’s the same story.

I receive lots of emails from novice growers asking me to recommend a special nutrient recipe or a bloom booster product that will guarantee them a marked increase in their yields. “Show us a shortcut, Everest!” they might as well say. Now, it would be easy for me to play up to this by giving myself a silly name (ahem!) growing my hair long, furrowing my brow, and working on my thousand-yard stare but instead I simply ask about their growing environment. Guess what? Nine times out of ten there are rudimentary problems that need to be addressed – such as high temperatures!

The hobby hydroponics industry is leading the way in terms of ‘spare-no-expense’ inputs for our gardens and, while many of these can constitute liquid heaven for our plants, we should remain cautious about becoming overly deferent to the claims on all the bottles. Sorry for the ‘inconvenient truth’ but no $400 tub of bloom booster is going to make up for crappy genetics and high temperatures in your indoor garden. Period.

First and foremost then, obtain good, strong plant genetics. Provide a healthy environment, give them a basic feed, avoid stress and you will enjoy good results. Get to that point first and then see where you can go from there. The ‘buy it in a bottle’ culture is well conditioned into us living in North America and it is all too easy for novice growers to think their paltry yields are down to the lack of a product, rather than a lack of basic skills in the garden.

We all want our gardens to be successful and to enjoy big, monster, jaw-dropping yields. But what are we prepared to do in order to reach our goals? Are we willing to spend time with our plants, to observe them closely every day, to invest time, money and effort into perfecting our indoor garden’s environment, searching out the finest plant genetics and understanding all the intricacies of our plants’ processes?

Or do we just want to buy some magic elixir in a bottle and let it do all the thinking, growing and blooming for us?

There, I said it. Doesn’t it feel good to be on the same page?

Everest

An extra word from Everest…